19mo sleeping habits

My 19mo has been waking up extremely early in the morning recently, about 5-6am. She used to sleep well, ie till 8am and takes 1 nap a day. Nap duration is around 2+/3hrs at about 12pm. Is she going through some sort of sleep regression for her to wake up so early? Also, recently, she learnt to climbed out of her crib onto the bed and come into our room, could it also contribute to her not waking up later? Because previously, if she wakes up early, we'll just let her try and put herself back to sleep, and she would. #advicepls